Strain-induced giant second-harmonic generation in monolayered 2H-MoX2 (X = S, Se, Te)

• DOI: 10.1063/1.4938120
• Publication Date: 2015-12-17T18:17:17Z
• Authors: S. H. Rhim; Yong Soo Kim; A. J. Freeman
• Keywords: Strain (injury); Chalcogen

Dynamic second-order nonlinear susceptibilities, $χ^{(2)}(2ω,ω,ω)\equiv χ^{(2)}(ω)$, are calculated here within a fully first-principles scheme for monolayered molybdenum dichalcogenides, $2H$-MoX$_2$ (X=S,Se,Te). The absolute values of $χ^{(2)}(ω)$ across the three chalcogens critically depend on band gap energies upon uniform strain, yielding highest $χ^{(2)}(0)\sim$ 140 pm/V MoTe$_2$ in static limit. Under this in-plane stress, can undergo direct-to-indirect transition gaps, which turn substantially affects $χ^{(2)}(ω)$. tunability by either compressive or tensile strain is demonstrated especially two important experimental wavelengths, 1064 nm and 800 nm, where resonantly enhanced non-linear effects be exploited: $χ^{(2)}$ MoSe$_2$ approach $\sim$800 with -2\% at nm.